Hydraulic fluid accumulator

ABSTRACT

The present invention discloses a hydraulic fluid accumulator comprising a housing ( 1 ) having an interior subdivided into three chambers ( 2, 3, 4 ), with the first chamber ( 2 ) being filled with a gas and separated from the second chamber ( 3 ) by a first media separation element ( 6 ), the second chamber being filled with a fluid and separated by a second media separation element ( 7 ) from the third chamber ( 4 ) that is also filled with a fluid and connected to a hydraulic port ( 5 ).  
     To safeguard an effective separation of media within the hydraulic fluid accumulator and, thus, a significant increase in its functional safety, the present invention arranges for the second media separation element ( 7 ) to be embodied by a metal piston ( 8, 80 ) delimiting a chamber ( 9, 19 ) that can be vented in the housing ( 1 ).

[0001] The present invention relates to a hydraulic fluid accumulator comprising a housing having an interior subdivided into three chambers, with the first chamber being filled with a gas and separated from the second chamber by a first media separation element, the second chamber being filled with a fluid and separated by a second media separation element from the third chamber that is also filled with a fluid and connected to a hydraulic port.

[0002] A hydraulic fluid accumulator of this type is disclosed in DE-OS 29 10 554. The first media separation element in the prior art hydraulic fluid accumulator is configured as a metal pleated bellows, while the second media separation element is provided by an elastic partition.

[0003] It is disadvantageous in the prior art hydraulic fluid accumulator that an effective separation of media cannot be achieved. Tests have shown that leakage at the pleated bellows that is usually absolutely gas-tight allows the gas to propagate from the first chamber into the second chamber, from there diffusing through the material of the elastic partition into the third chamber. This causes a massive entry of gas into the hydraulic system equipped with the hydraulic fluid accumulator what cannot be recognized in time.

[0004] Therefore, an object of the present invention is to improve upon a hydraulic fluid accumulator of the type mentioned hereinabove so that the entry of gas into the following hydraulic system is prevented, thereby ensuring a significant increase in the reliability in operation.

[0005] According to the present invention, this object is achieved in that the second media separation element is formed of a metal piston delimiting a chamber that is adapted to be vented.

[0006] Extremely compact constructions of the subject matter of the present invention are achieved in that the piston is sealed and guided in the housing and embraces the first media separation element in a radial direction and, respectively, that the first chamber is designed between the wall of the housing and the first media separation element and that both the second and the third chamber is provided within the first media separation element.

[0007] Favorable improvements of the subject matter of the present invention are listed in the sub claims 2 and 5 to 8.

[0008] The present invention will be explained in more detail in the following description of two embodiments by making reference to the accompanying drawings. In the drawings,

[0009]FIG. 1 is an axial sectional view of a first embodiment of the hydraulic fluid accumulator of the present invention.

[0010]FIG. 2 shows an illustration corresponding to FIG. 1 of a second embodiment of the hydraulic fluid accumulator of the present invention.

[0011] The first embodiment of the hydraulic fluid accumulator of the present invention as shown in FIG. 1 comprises a housing 1 having an interior that is subdivided into three pressure compartments or chambers 2, 3, 4. The first chamber 2 is formed by the inner space of a first media separation element 6 that is preferably composed of a thin-walled metal pleated bellows being connected pressure-tightly to the housing 1, on the one hand, and closed by a plate 13, on the other hand. The first chamber 2 can be filled with a gas that is normally under high pressure through a fill port (not shown) arranged in housing 1. A piston 8 preferably made of metal, that is guided in housing 1 so as to be displaceable and encompasses the above-mentioned pleated bellows 6 in a radial direction, confines with the pleated bellows 6 the second chamber 3 and forms a second media separation element designated by reference numeral 7. Incorporated in the bottom part of the housing 1 is the third chamber 4, a hydraulic port 5 opening into said chamber. A radial recess arranged at the periphery of the piston 8 along with the wall of housing 1 defines a compartment 9 which is in communication with the atmosphere by way of bores 14. The compartment 9 is sealed in relation to the second chamber 3 or, respectively, the third chamber 4 by means of each one elastic ring seal 11 or 12, respectively. When brake fluid is used to fill the second chamber 3, it is possible to connect the above-mentioned compartment 9 to a brake fluid reservoir. To reduce the natural leakage at the first-mentioned ring seal 11, it is also possible to use a particularly viscous fluid for filling the second chamber 3, with the said fluid, however, being then discharged into e.g. the atmosphere rather than into the brake fluid reservoir.

[0012] In the second embodiment of the subject matter of the present invention illustrated in FIG. 2, the first chamber 20 is not formed by the inner space of the first media separation element 60, as described above, but is delimited between the wall of the housing 10 and the first media separation element or pleated bellows 60. The inner space of the pleated bellows 60 forms the second chamber 30 projecting into which is a cylindrical guide element 15 that is associated with the housing 10, in which the second media separation element 70 or, respectively, the piston 80 is guided and the third chamber 40 is arranged. The compartment 90 mentioned with respect to FIG. 1 and defined between the piston 80 and the cylindrical guide element 15—similar to the embodiment shown in FIG. 1 —is sealed in relation to the second chamber 30 and the third chamber 40, respectively, by each one ring seal 110, 120 and connects to the atmosphere by way of a schematically shown channel 18. Further, piston 80 includes a hydraulic connection 19 between the second and the third chamber 30, 40 wherein a non-return valve 17 closing towards the third chamber 40 is inserted. The non-return valve 17 is used to fill and, respectively, replenish separating fluid into the second chamber 30. 

1. Hydraulic fluid accumulator comprising a housing (1, 10) having an interior subdivided into three chambers (2, 3, 4, 20, 30, 40), with the first chamber (2, 20) being filled with a gas and separated from the second chamber (3, 30) by a first media separation element (6, 60), the second chamber being filled with a fluid and separated by a second media separation element (7, 70) from the third chamber (4, 40) that is also filled with a fluid and connected to a hydraulic port (5, 50), characterized in that the second media separation element (7, 70) is formed of a metal piston (8, 80) delimiting a chamber (9, 90) that is adapted to be vented in the housing (1, 10).
 2. Hydraulic fluid accumulator as claimed in claim 1, characterized in that the first media separation element (6, 60) and the second media separation element (7, 70) are arranged coaxially.
 3. Hydraulic fluid accumulator as claimed in claim 1 or 2, characterized in that the piston (8) is guided in the housing (8) so as to be displaceable and sealed and embraces the first media separation element (6) in a radial direction.
 4. Hydraulic fluid accumulator as claimed in claim 1 or 2, characterized in that the first chamber (20) is arranged between the wall of the housing (10) and the first media separation element (60), and that the second chamber (30) and the third chamber (40) are provided within the first media separation element (60).
 5. Hydraulic fluid accumulator as claimed in claim 4, characterized in that the second chamber (30) is delimited by the first media separation element (60), on the one hand, and by a cylindrical guide member (15), on the other hand, in which the third chamber (40) is designed and the piston (80) is guided.
 6. Hydraulic fluid accumulator as claimed in claim 5, characterized in that incorporated in the piston (80) is a hydraulic connection (16) between the second chamber (30) and the third chamber (40), with a non-return valve (17) closing towards the hydraulic port (50) being inserted into said connection.
 7. Hydraulic fluid accumulator as claimed in claim 3, characterized in that the piston (8) is a component of a travel measuring system.
 8. Hydraulic fluid accumulator as claimed in any one of claims 2 to 7, characterized in that the chamber (9, 90) that can be vented is sealed in relation to the second chamber (3, 30) and the third chamber (4, 40) by means of two elastic seals (11, 12, 110, 120), preferably ring seals. 